Sang-Kyoo Han

A New Phase-Shifted Full-Bridge Converter With Voltage-Doubler-Type Rectifier for High-Efficiency PDP Sustaining Power Module

A new phase-shifted full-bridge converter with a voltage-doubler-type rectifier for a high-efficiency power-sustaining module of a plasma display panel is proposed in this paper. The proposed converter employs a voltage-doubler rectifier without an output inductor. Since it does not have an output inductor, the voltage stresses of the rectifier diodes can be clamped at the output voltage level. Thus, since no dissipative resistor-capacitor snubber for rectifier diodes is needed, high-efficiency low-noise output voltage can be realized. Due to the elimination of the large output inductor, it features simpler structure, lower cost, smaller mass, and lighter weight. Furthermore, the proposed converter has wide zero-voltage-switching ranges of lagging leg switches with low current stresses of the primary power switches by using the magnetizing current. In addition, the resonance between the leakage inductor of the transformer and the rectifier capacitors can reduce the current stresses of the rectifier diodes and conduction losses. In this paper, the operational principles, analysis, design considerations, and experimental results are presented.

High-Efficiency and Low-Cost Tightly Regulated Dual-Output

A new high-efficiency and cost-effective dualoutput LLC resonant converter is proposed in this paper. The proposed converter can get tightly regulated dual-output voltages by adding only one auxiliary switch and PWM IC to conventional LLC resonant converter. Therefore, it features a simpler structure, less mass, and lower cost of production. Furthermore, since all power switches are turned on or off under zero-voltage switching (ZVS) or zero-current switching (ZCS), it has several favorable advantages such as high-efficiency, low switching loss, improved electromagnetic interference (EMI), and reduced burden on the cooling system. This paper presents a dual-output LLC resonant converter applicable to the PDP TV power supply. The proposed converter achieves maximum power conversion efficiency of 96.5% at full load condition. The operational principle, theoretical analysis, and design considerations are presented. Also, to confirm the operation, validity and features of the proposed converter, experimental results from a 420W, 200Vdc/50Vdc prototype are presented.

LLC

The conventional zero-voltage switching phase-shift full-bridge (ZVS PSFB) converter has a large circulating energy during the freewheeling interval caused by the small duty cycle, which could increase the primary-side conduction losses, the turn-off switching losses of lagging-leg switches, and the current ripple through the output inductor. To overcome these problems, this paper proposes a new pulse-frequency-modulated full-bridge direct-current (dc)/dc converter with a series boost capacitor (SBC). The proposed converter controls the output voltage by varying the voltage across the SBC according to the switching frequency and has no freewheeling interval due to a 50% fixed duty operation. As a result, since its freewheeling current is eliminated, the conduction losses can be considerably reduced, as compared with those of the conventional ZVS PSFB converter. Moreover, the ZVS of all power switches cannot only be ensured along wide load ranges, but the current ripple through the output inductor can be also significantly reduced. Therefore, it has very desirable merits such as high efficiency, small output inductor, and improved heat generation. Operational principles, theoretical analysis, and design considerations are presented. To confirm the operation, the validity, and the features of the proposed converter, experimental results from a prototype that is 400-12 V/100 A are presented.

Resonant Converter

A new high efficiency active clamp forward converter for the sustaining power module of a plasma display panel is proposed. It features zero voltage switching, a simpler structure, lower cost, less mass, and no effective duty loss. Furthermore, voltages across all rectifier diodes are clamped on the output voltage, which results in higher efficiency.

A Pulse-Frequency-Modulated Full-Bridge DC/DC Converter With Series Boost Capacitor

A new voltage doubler rectified boost-integrated half bridge converter for digital car audio amplifiers is proposed. The proposed converter shows low conduction loss due to low voltage stress of the secondary diodes, no dc magnetizing current for the transformer, and a lack of stored energy in the transformer. Moreover, since the primary MOSFETs are turned-on under zero voltage switching conditions and the secondary diodes are turned-off under zero current switching conditions, the proposed converter has minimized switching losses. In addition, the input filter can be minimized due to a continuous input current, and an output filter does not need an inductor in the proposed converter. Therefore, the proposed converter has the desired features, high efficiency and low profile, for a viable power supplies for digital car audio amplifiers. A 60-W industrial sample of the proposed converter has been implemented for digital car audio amplifiers with a measured efficiency of 88.3% at nominal input voltage.

High Efficiency Active Clamp Forward Converter for Sustaining Power Module of Plasma Display Panel

A zero-voltage switching (ZVS) and soft-commutating two-transformer full-bridge pulsewidth modulation converter using the voltage ripple is proposed in this paper. It is based on the phase-shift full-bridge with series-connected two transformers (TTFB) that act as an output inductor as well as a main transformer. Moreover, the TTFB converter achieves the ZVS of all the switches inherently even at a light load using the energy stored in the magnetizing inductance of each transformer. However, it has several drawbacks such as circulating energy during the freewheeling state, loss of duty cycle, and high voltage stress across the output rectifier diodes. To overcome these drawbacks, the proposed converter employs an output-voltage-doubler, allowing the output rectifier diode to softly commutate with less voltage stress, to reduce the freewheeling interval as well as the circulating energy. The operational principle, technical analysis, and design considerations are described. Finally, the experimental results from a 425 W, 385 Vdc /170 Vdc prototype are presented to confirm the operation, validity, and features of the proposed converter.

Voltage Doubler Rectified Boost-Integrated Half Bridge (VDRBHB) Converter for Digital Car Audio Amplifiers

A high-performance and low-cost single-switch current-fed energy recovery circuit (ERC) for an alternating current (ac) plasma display panel (PDF) is proposed. Since it is composed of only one power switch compared with the conventional circuit consisting of four power switches and two large energy recovery capacitors, it features a much simpler structure and lower cost. Furthermore, since all power switches can be switched under soft-switching operation, the proposed circuit has desirable merits such as an increased reliability, and low switching loss. Especially, there are no serious voltage notches across the PDP with the aid of gas discharge current compensation, which can greatly reduce the current stress of all inverter switches, and provide those switches with the turn on timing margin. To confirm the validity of the proposed circuit, its operation and performance were verified on a prototype for 7-in test PDP.

Zero-Voltage Switching and Soft-Commutating Two-Transformer Full-Bridge PWM Converter Using the Voltage-Ripple

A new current-balancing multi-channel LED driver is proposed in this paper. The conventional LED driver system consists of three cascaded power conversion stages and its driver stage has the same number of expensive boost converters as those of the LED channels. On the other hand, the proposed LED driver system consists of two cascaded power stages and its driver stage requires only passive devices instead of expensive boost converters. Nevertheless, all of the currents through multi-channel LEDs can be well balanced. Therefore, it features a smaller system size, improved efficiency, and lower cost. To confirm the validity of the proposed driver, its operation and performance are verified on a prototype for a 46” LCD TV.

High-Performance and Low-Cost Single-Switch Current-Fed Energy Recovery Circuit for ac Plasma Display Panel

A new high-efficiency and cost-effective dualoutput LLC resonant converter is proposed in this paper. The proposed converter can get tightly regulated dual-output voltages by adding only one auxiliary switch and PWM IC to conventional LLC resonant converter. Therefore, it features a simpler structure, less mass, and lower cost of production. Furthermore, since all power switches are turned on or off under zero-voltage switching (ZVS) or zero-current switching (ZCS), it has several favorable advantages such as high-efficiency, low switching loss, improved electromagnetic interference (EMI), and reduced burden on the cooling system. This paper presents a dual-output LLC resonant converter applicable to the PDP TV power supply. The proposed converter achieves maximum power conversion efficiency of 96.5% at full load condition. The operational principle, theoretical analysis, and design considerations are presented. Also, to confirm the operation, validity and features of the proposed converter, experimental results from a 420W, 200V dc /50V dc prototype are presented.

A New Cost-Effective Current-Balancing Multi-Channel LED Driver for a Large Screen LCD Backlight Units

A new three phase three-level pulsewidth modulation (PWM) switched voltage source inverter with zero neutral point potential is proposed. It consists of three single-phase inverter modules and each module is composed of a switched voltage source and inverter switches. The major advantage is that the peak value of the phase output voltage is twice as high as that of the conventional neutral-point-clamped PWM inverter. Thus, the proposed inverter is suitable for applications with low voltage sources such as batteries, fuel cells, or solar cells. Furthermore, three-level waveforms of the proposed inverter can be achieved without the switch voltage unbalance problem. Since the average neutral point potential of the proposed inverter is zero, a common ground between the input stage and the output stage is possible. Therefore, it can be applied to a transformerless power conditioning system. The proposed inverter is verified by a PSpice simulation and experimental results based on a laboratory prototype